1. Field of the Invention
The present invention relates to a method and apparatus for correlating the named day of the week to a past or future date as specified by the year, month and numerical day of the month.
2. Description of the Prior Art
The occidental method of measuring a solar year with 365 days punctuated every fourth year by 366 days was decreed in 45 B.C. by Julius Caesar. Although this Julian Calendar was a vast improvement over prior methods of solar year measurement, it nevertheless was in error by about eleven minutes per year. By the year 1582, the Julian Calendar was proceeding with a 10 day error.
In the year 1582, Pope Gregory XIII decreed that the day following Oct. 4, 1582 would become Oct. 15, 1582. Moreover, those centesimal years (ending in 00) not evenly divisible by 400 would not be leap years, i.e., the respective February would have only 28 days. In operation, therefore, the centesimal year of 1600 had a 29 day February. The subsequent centesimal years of 1700, 1800 and 1900 had only 28 day Februaries. However, the forthcoming centesimal year of 2000 will again have a 29 day February.
This Gregorian modification of the Julian Calendar perpetrates an error of less than one day per 3000 years. No further correction is anticipated before the year 4600.
In the interim, cultural evolution has attached great significance to the seven day division of the 52 solar weeks. Although watershed dates of history are usually recorded in terms of the year, month and date, there are occasions when the day-name of the week the event occurred is as important as the year, month and day number.
Serious historians and long term event planners have need for a convenient and reliable method and or apparatus for assigning the correct week day name to a particular numbered day of the month in any year, past and future.
Prior art for such need has been represented by a system that correlates one of fourteen annual calendars to each year from 1700 to 2108 only. There is no orderly procedure to extrapolate from this date delineated interval.